-    CALCITE     -    CaCO3

The crystal structure is fully relaxed (both unit cell parameters and atomic positions under symmetry constraints) at 2GPa starting from an experimental structure similar to the one reported in AMCSD 

Crystal Structure 


Because of the translational symmetry all the calculations are performed in the primitive unit cell and not in the conventional unit cell. The following information regarding the structure is given with respect to this primitive unit cell, which sometimes can take an unintuitive shape.

Symmetry (experimental): 

Space group:  167  R-3c 
Lattice parameters (Å):  5.0492  5.0492  17.3430 
Angles (°):  90  90  120 

Symmetry (theoretical): 

Space group:  167  R-3c 
Lattice parameters (Å):  6.1655  6.1655  6.1655 
Angles (°):  47.73  47.73  47.73 

Cell contents: 

Number of atoms:  10 
Number of atom types: 
Chemical composition: 

Atomic positions (theoretical):

Ca:  0.0000  0.0000  0.0000 
C:  0.2500  0.2500  0.2500 
O:  0.5056  0.9944  0.2500 
O:  0.9944  0.2500  0.5056 
Ca:  0.5000  0.5000  0.5000 
C:  0.7500  0.7500  0.7500 
O:  0.7500  0.4944  0.0056 
O:  0.2500  0.5056  0.9944 
O:  0.4944  0.0056  0.7500 
O:  0.0056  0.7500  0.4944 
Atom type 

We have listed here the reduced coordinates of all the atoms in the primitive unit cell.
It is enough to know only the position of the atoms from the assymetrical unit cell and then use the symmetry to build the whole crystal structure.

Visualization of the crystal structure: 

Size:

  
Nx:  Ny:  Nz:    
You can define the size of the supercell to be displayed in the jmol panel as integer translations along the three crys­tallo­gra­phic axis.
Please note that the structure is represented using the pri­mi­tive cell, and not the conventional one.
     

Powder Raman 

Powder Raman spectrum

The intensity of the Raman peaks is computed within the density-functional perturbation theory. The intensity depends on the temperature (for now fixed at 300K), frequency of the input laser (for now fixed at 21834 cm-1, frequency of the phonon mode and the Raman tensor. The Raman tensor represents the derivative of the dielectric tensor during the atomic displacement that corresponds to the phonon vibration. The Raman tensor is related to the polarizability of a specific phonon mode.

Horizontal:
Xmin:
Xmax:
Vertical:
Ymin:
Ymax:
 
Choose the polarization of the lasers.
I ∥ 
I ⊥ 
I Total 

Data about the phonon modes

Frequency of the transverse (TO) and longitudinal (LO) phonon modes in the zone-center. The longitudinal modes are computed along the three cartesian directions. You can visualize the atomic displacement pattern corresponding to each phonon by clicking on the appropriate cell in the table below.

1
Ac
0
0
0
0
2
Ac
0
0
0
0
3
Ac
0
0
0
0
4
A2u
63
63
63
91
5
Eu
91
91
91
91
6
Eu
91
116
116
129
7
A2g
167
167
167
167
8
Eg
171
171
171
171
4.953e+39
7.6
6.220e+39
9.5
1.117e+40
17.1
9
Eg
171
171
171
171
4.953e+39
7.6
7.977e+39
12.2
1.293e+40
19.8
10
Eu
268
268
268
268
11
Eu
268
283
283
268
12
A1u
312
312
312
312
13
Eg
322
322
322
322
1.162e+40
17.8
1.704e+40
26.1
2.866e+40
43.9
14
Eg
322
322
322
322
1.162e+40
17.8
1.167e+40
17.9
2.329e+40
35.7
15
A2g
357
357
357
357
16
Eu
369
369
369
369
17
Eu
369
387
387
369
18
A2u
387
434
434
456
19
Eg
714
714
714
714
2.399e+39
3.7
2.740e+39
4.2
5.139e+39
7.9
20
Eg
714
714
714
714
2.399e+39
3.7
2.087e+39
3.2
4.486e+39
6.9
21
Eu
719
719
719
719
22
Eu
719
721
721
719
23
A2u
846
846
846
852
24
A2g
852
852
852
864
25
A1u
1108
1108
1108
1108
6.340e+40
97.0
1.930e+39
3.0
6.534e+40
100.0
26
A1g
1108
1108
1108
1108
2.143e+39
3.3
6.525e+37
0.1
2.209e+39
3.4
27
Eu
1434
1434
1434
1434
28
Eu
1434
1462
1462
1434
29
Eg
1462
1462
1462
1462
2.241e+39
3.4
2.196e+39
3.4
4.437e+39
6.8
30
Eg
1462
1578
1578
1462
2.241e+39
3.4
2.275e+39
3.5
4.516e+39
6.9
No.  Char.  ω TO  ω LOx  ω LOy  ω LOz  I ∥  I ⊥  I Total 
You can define the size of the supercell for the visualization of the vibration.
Nx: 
Ny: 
Nz: 
Normalized
Raw
Options for intensity.